/ 


-I 

CHANGE  IN  MOISTURE  CONTENT  CE 
LUMBER  DURING  RAIL  SHIPMENT 

December  1927 

SCHOOL  OF  FORESTRY  LIBRARY 

UNIVERSITY  OF  FLORIOA 


No.  R826 


UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 
FOREST    SERVICE 
FOREST   PRODUCTS    LABORATORY 
Madison.     Wisconsin 

In     Cooperation     with     the    University    of     Wisconsin 


CHAI7GS  IIT  MOISTURE  CONTENT  07  LUMBER  DURING-  RAIL  SHIPMENT^ 


By 


G.  E.  FRENCH, 
Assistant  Wood  Technologist 


Engineers  are  interested  in  the  degree  of  seasoning  at  which  standard  sizes 
of  lumber  apply,  and  frequently  also  in  the  possibility  of  obtaining  lumber  of 
some  specific  moisture  content  that  fits  it  for  a  special  use  without  the  risk 
of  changes  in  dimension  due  to  shrinkage  and  swelling-   It  is,  therefore,  im- 
portant to  know  to  what  extent  the  moisture  content  of  lumber  changes  during 
the  ltng  rail  hauls  that  are  now  a  common  necessity  of  lumber  marketing. 

This  paper  presents  the  results  of  an  investigation  made  to  determine  whether 
or  not  lumber  placed  aboard  cars  at  the  sawmill  at  a  low  moisture  content  will 
change  in  moisture  content  during  transit  to  such  a  degree  as  to  defeat  the 
purpose  of  careful  seasoning  for  general  or  specific  uses. 

As  a  preliminary  step  in  the  study,  representatives  of  the  Forest  Products 
Laboratory  and  of  the  Forest  Service  district  products  office,  Missoula,  Moat.,, 
early  in  1926  determined  the  change  in  moisture  content  of  six  carloads  of 
lumber  shipped  from  Idaho  to  the  vicinity  of  Chicago.   The  late  winter  and 
spring  season  was  selected  as  the  time  for  the  tests  because  this  is  the 
period  of  highest  humidity  of  the  year.   In  the  six  cars  tested  containing 
largely  inch-thick  flat  stock  of  white  fir,  ponderosa  pine,  and  western  white 
pine,  the  moisture  change  of  material  while  in  transit  was  slight  except  for 
some  material  with  30  percent  average  moisture  content  that  lost  about  5  percent. 

In  view  of  the  small  changes  which  these  shipments  showed,  the  Forest  Products 
Laboratory  decided  in  1927  to  determine  not  only  the  change  in  average  mois- 
ture content  for  carloads  of  lumber,  but  to  show  in  what  portion  of  the  laad 
local  changes,  if  any,  were  taking  place.   The  cooperating  company,  whose 
plant  is  located  in  western  Oregon,  was  shipping  clear  grades  of  Douglas.-fir 
kiln  dried,  to  an  average  of  8  percent  moisture  content  and  common -grades  of 
Douglas-fir  kiln  dried  to  approximately  20  percent.  Five  cars  of  flat  clears 
were  tested,  one  car  of  clear  quarter-round  and  erown  molding,  and  one  car  of 
common  shiplap.  Eighteen  sample  boards  were  placed  in  the  same  relative  po- . 
sition  in  each  car.   They  were  protected  from  any  extra  moist  boards  in  the 
vicinity  by  being  placed  between  check  boards  of  approximately  the  same  mois- 
ture content  as  the  sample.  Each  sample  board  was  sampled  for  moisture  content 
and  weighed  to  the  nearest  hundredth  of  a  pound  at  the  time  it  was  placed  in 
the  car.  At  destination  (Chicago)  the  sample  boards  were  again  weighed  and  \ 
moisture  content  tests  were  made.  As  a  check  upon  these  two  methods  of  deter- 
mining the  change  in  moisture  content  the  total  weight  of  each  shipment  was 

-Published  in  Furniture  Manufacturer,  Dec.  1927. 
RS26 


determined  at  the  point  of  origin  and  destination  "by  weighing  the  car  loaded 
and  empty.   The  results  obtained  "by  all  three  methods,  namely,  (l)  change  in 
weight  of  sample  boards,  (?)   change  in  weight  of  total  shipment,  and  (3)  change 
determined  "by  moisture  content  determinations  of  the  samples  at  origin  a 
destination,  were  so  similar  that  only  those  changes  shown  "by  the  sample  "board 
weights  need  "be  considered  here. 

The  data  obtained  are  shown  in  the  accompanying  table  and  illustrated  graph- 
ically in  the  diagrammatic  cross-section  of  the  freight  car.  Tor  the  five 
cars  of  flat  clear  Douglas-fir  the  average  change  in  moisture  content  was  a 
0.2  percent  increase  (based  on  the  oven-dry  weight  of  the  samples);  for  the 
more  loosely  loaded  molding,  0.8  percent  increase;  and  for  the  common  lumber 
a  loss  of  C.4  percent.  The  changes  were  so  small  as  to  fall  well  within  the 
possible  error  of  moisture  determinations.   The  samples  distributed  throughout 
the  loads  gave  no  definite  indications  of  local  changes.  As  all  of  those 
shipments  were  made  from  the  West  Coast  two-thirds  of  the  way  across  the  con- 
tinent, with  only  the  ordinary  precautions  used  in  loading  box  cars  during  the 
wettest  period  of  the  year,  it  is  quite  reasonable  to  conclude  that  during  the 
usual  haul  in  good  box  cars  no  appreciable  change  in  moisture  content  of 
lumber  need  be  expected. 

This  information  is  significant.   It  means  that  stock  placed  in  the  car  in 
satisfactory  condition  as  to  moisture  content  will  reach  the  unloading  point 
in  practically  the  same  condition.   If,  on  the  other  hand,  it  is  received  in 
bad  condition  by  the  consignee,  the  fault,  unless  the  car  is  in  a  poor  state 
of  repair,  must  be  with  the  seasoning  methods'  employed. 

The  virtual  elimination  of  this  "unknown"  between  shipper  and  consignee  brings 
the  moisture  content  problem  one  step  nearer  solution. 

Change  in  moisture  content  of , Douglas-fir  lumber  shipped  by  rail  during 
the  winter  season  from  the  West  Coast  to  the  vicinity  of  Chicago. 


Carload 

shipment 
number 


Date 
shipped 


Date   ; 
reached  : 
consignee: 
j. 


Grade 


Average  mo  is-:  Change  in 
ture  content  : moisture  con- 
when  loaded  stent  in  transit 


1 
2 

3 
U 

5 
Av. 

s 


'  1.  25" 

Feb.  k 

Pec.  10 
Mar.  18 
Mar.  25 


1927 


Feb.  10 

Feb,  28 

Mar.  U 

Apr.  5 

Apr .  16 


May  25 
May  2U 


Clears 
11 
11 
11 
11 


Quarter-round  and 

crown  moulding 
Common 


Percent 


8 

8 

10 

9 

7 

..8 

8 


21.0 


+ 

0.2 

+ 

0.3 

+ 

0.3 

- 

0.1 

+ 

0.3 

+ 

0.2; 

+ 

O.S 

-  O.U 


R326 


UNIVERSITY  OF  FlORIDA 


3  1262  08929  1842 


o.ctf 


+0.3* 


1-o.iJ] 


+0 


.6*1 


+0,2* 


+0.3* 


+0 


iii) 


j,Q.lftj 


+0.8*1 


Average  change  0.2* 


0.0* 


+0.U* 


j-0,2* 


-0.2* 


B] 


+0.3'* 


<* 


+0.2* 


+0,6* 


+0.5  * 


Diagrammatic  cross  section  of  freight  car  as  loaded  with  clear  grades 

of  Douglas -fir.     The  small  rectangles   indicate  the  location  of 

the  sample  "boards  within  load  in  the  1927  tests,     Figures   in 

small  rectangles  show  average  local  change  in  moisture 

content  of  lumber  during  transit. 


R826 


